1. Field of the Invention
The present invention relates to polymer particles with a narrow particle size distribution, which can be employed as spacers for use in electronic appliances, a filler for use in a high functional separation column, a molding material, a coating material, and microspheres having active surfaces for use in antigen-antibody reactions, and to a method of producing the polymer particles, and also to a toner for use in electrophotography comprising the polymer particles.
2. Discussion of Background
As the inventors of the present invention have disclosed in Japanese Laid-Open Patent Application 61-19602, polymer particles with a narrow particle size distribution in the range of 1 to 20 .mu.m can be obtained under particular conditions by a polymerization method of polymerizing a vinyl monomer in a hydrophilic organic liquid.
Based on this polymerization method, many trials have been made for changing the composition and physical properties of the surface of polymer particles by using a different kind of polymer stabilizing agent or by providing chemical modifications to the surface of the polymer particles.
However, polymer particles obtained by this polymerization method are substantially spherical and trials for changing the shape of the polymer particles by using this polymerization method have not been made.
With respect to the field of toners for use in electrophotography, a toner comprising such spherical polymer particles with a small particle diameter and a narrow particle size distribution is suitable for high quality digital latent electrostatic images because the toner provides high quality images. However because the polymer particles employed in the toner have a small particle size and are spherical, the cleaning performance, image transfer performance and chargeability of the toner, in particular, the chargeability at high humidities, are so poor that such a toner has not been employed in practice.
Japanese Laid-Open Patent Application 61-279864 discloses toner particles with the degree of the distortion from the complete spherical shape of the toner particles being described in terms of the shape factor thereof and with the degree of the unevenness of the surface of the toner particles being limited to a certain value. However, the reference does not mention anything about factors which have significant effects on the characteristics of the toner, such as the particle size distribution of the toner and the composition of the protrusions on the surface of the toner particles.
Japanese Laid-Open Patent Application 1-185653 discloses a toner comprising toner particles which have a relatively narrow particle size distribution and are nearly spherical. However, the toner particles thereof have very small protrusions or substantially crushed protrusions on the surface thereof, so that the height and composition of the protrusions have not been taken into consideration when using the toner particles.
Furthermore, Japanese Laid-Open Patent Applications 1-300264 and 2-187768 describe methods comprising the steps of preparing polymer particles and attaching finely-divided particles to the surface of the polymer particles in order to make the surface of the polymer particles uneven. However, the methods described in the above references have the shortcomings that the finely-divided particles are not completely attached to the surface of the polymer particles, so that some of the finely-divided particles are detached from the surface of the polymer particles, and the finely-divided particles are deformed. Furthermore, it is impossible to attach relatively large particles to the polymer particles by the above methods in order to make the surface of the polymer particles largely uneven.